1. Field of the Invention.
The present invention relates to a cooling system for a plurality of circuit boards each having a substantially planar thermally conductive thermal sink having longitudinal sides and in thermal contact with a plurality of electronic components dissipating heat, in particular cooling system including a heat exchanger to deliver heat to a cooling medium and heat pipe means to transfer heat from said thermal sinks to said heat exchanger.
2. Background Information
Such a cooling system is already known from the non-published PCT patent application No PCT/EP89/01613 (F. Leyssens et al 11-4-1) first filed by Applicant on Dec. 28, 1989. Therein the heat pipe means comprises sets of heat conductive metal rails housing heat pipes. More particularly, two sets of first metal rails arranged in two parallel planes and housing first heat pipes make thermal contact with respective opposite longitudinal sides of the thermal sinks of the circuit boards. Two sets of second metal rails including second parallel heat pipes and mounted in a plane perpendicular to those containing the first metal rails makes thermal contact therewith. Finally, a third metal rail housing third heat pipes and mounted in a plane perpendicular to those containing the first and second metal rails makes thermal contact with the second rails and leads to the heat exchanger.
A drawback of this known cooling system is that the thermal resistance between the thermal sinks and the heat exchanger is still relatively high, especially due to the fact that the heat transfer between these elements does not take place directly via the heat pipes but through the intermediary of a plurality of metal rails which thermally link the thermal sinks, heat pipes and heat exchanger and which present a relatively high thermal resistance especially at their junctions.